Integrins are a superfamily of cell surface receptors that mediate cell-cell and cell-matrix adhesion. These heterodimeric proteins, composed of two noncovalently linked polypeptide chains, α and β, provide anchorage as well as signals for cellular growth, migration and differentiation during development and tissue repair. Integrins have also been implicated in immune and inflammatory processes, which require the extravasation of cells out of blood vessels, into tissues and towards the site of infection.
VLA-1 (also called α1β1) belongs to a class of integrins called VLA (“Very Late Antigen”) integrins. VLA-1 binds collagen (both types I and IV) and laminin, and has been implicated in cell adhesion and migration on collagen; contraction and reorganization of collagen matrices; and regulation of expression of genes involved in extracellular matrix remodeling.
VLA-1 has been shown to be involved in the development of rheumatoid arthritis, a chronic inflammatory disease associated with bone resorption. Infiltrating T cells in the arthritic synovium of patients express high levels of VLA-1, and its blockade with antibodies significantly reduces the inflammatory response and the development of arthritis in animal models.